The present invention relates to a gas laser apparatus, in which a longitudinal axis of a dielectric tube in which a laser medium gas is excited by electric discharge to generate a laser beam is substantially identical to an axis of the generated laser beam, and/or a microwave is used to excite the laser medium gas.
In a conventional gas laser apparatus, the laser medium gas flows into the dielectric tube from a passage whose central axis crosses perpendicularly the longitudinal axis of the dielectric tube, and a plurality of microwaves with respective induction electric-field directions different from each other are used to generate the electric discharge.